This invention relates to a heat exchanger for electronic or electrical components. More specifically, it relates to such a heat exchanger that is ideally suited for use in cooling electronic and/or electrical components in a vehicle utilizing the coolant employed for cooling an internal combustion engine which provides the source of propulsion for the vehicle.
Heat exchangers for cooling electronic and/or electrical components in a vehicle are being employed with ever-increasing frequency. It is common knowledge that electronic components which produce heat during operation must be cooled in order to avoid damage to the component and/or printed circuits connecting components on a circuit board. An example of such a heat exchanger is disclosed in EP 1,096,647 A2. The heat exchanger of the above-referenced European patent apparently utilizes an oil as a coolant. The device is intended for use in cooling power electronics as, for example, those utilized in the operation of a combination starter-generator and can be used to control other electronic or electrical components utilized for steering in vehicle control as, for example, electric motors in the vehicle.
It appears that such heat exchangers employed for cooling of electrical or electronic components could utilize a coolant already present on the vehicle utilized for cooling other instrumentalities as, for example, cooling the vehicle""s internal combustion engine as such a coolant is circulated in a coolant circuit at the present time.
Cooling of vehicular electronic or electrical components utilizing the circulating engine coolant differs from evaporative cooling where heat rejected by the components to be cooled causes the coolant to undergo a liquid to vapor phase change as heat is rejected into the coolant. A particular difference resides in the fact that in evaporative cooling, an entire circuit board with the electronic components to be cooled is placed in a housing and submerged in an electrically nonconducting heat exchange fluid. The advantage here is that all of the electronic components, which, because of their different nature, reject different quantities of heat during their operation, are subject to cooling so that overheating of all individual components can be avoided. One such evaporative-type cooler is disclosed in unpublished German patent application DE 101 58 387.7.
On the other hand, cooling with an already present coolant, such as engine coolant as mentioned previously, involves a problem quite different from that encountered where the components to be cooled are submerged in a coolant subject to phase change. In particular, in an apparatus such as a vehicle, the engine coolant pump is typically in operation to circulate coolant only when the engine is running. This may be referred to as a xe2x80x9cdynamicxe2x80x9d cooling operation.
Other components requiring cooling must then be subjected to a design that allows cooling only when coolant is being circulated by a pump or be such that their cooling requirements are minimal, allowing sufficient cooling of them to occur during dynamic cooling operation. However, cases of design and operation occur that require electronic components to be cooled even when the coolant pump is not in operation and coolant is not circulating. This may be referred to as static cooling operation. An example of such a system that can incur cooling problems during static operation is disclosed in German patent publication DE 199 59 023 A1. It cannot respond to the need for cooling of electronic components during static operation because the housing of the device disclosed therein is added as an auxiliary housing to the housing of the coolant circulating pump; and the coolant flows through the auxiliary housing only, if at all, when the coolant pump is in operation, that is, when the system is undergoing dynamic cooling operation.
The present invention is directed to solving one or more of the above problems.
It is the principal object of the invention to provide a new and improved heat exchanger for the cooling of electronic or electrical components. More particularly, it is an object of the invention to provide such a heat exchanger that may be utilized in a system having a coolant circulating pump and which provides adequate cooling for the components to be cooled whether the cooling system is operating in a dynamic cooling mode or in a static cooling mode.
An exemplary embodiment achieves the foregoing object in a heat exchanger for cooling electronic or electrical components which includes a circuit board on which the components to be cooled are mounted and a coolant channel with a coolant inlet and a coolant outlet in heat exchange contact with the circuit board. The invention contemplates the improvement that includes a container defining a coolant receiving space or depot adjacent to and in heat exchange relation with the flow channel and adapted to contain a coolant to accept heat rejected by the components when the coolant is not flowing in the coolant channel between the inlet and the outlet.
As a consequence of this construction, when the coolant is flowing in the flow channel during dynamic operation, it provides a stream of coolant to which heat from the components may be rejected. At the same time, when coolant is not flowing in the coolant channel (static operation), heat rejected by the components is rejected to coolant in the coolant depot.
In a preferred embodiment, a fluid connection establishing fluid communication between the container and the flow channel is provided.
In a preferred embodiment, there is provided a heat exchanger that includes a first cup-like component having a bottom and a peripheral wall about the bottom, and a second cup-like component having a bottom and a peripheral wall about its bottom. The second component is nested within the first component with their bottoms and peripheral walls spaced from one another to define a coolant flow channel therebetween. A circuit board mounting components to be cooled is mounted on the first component bottom in heat conducting relation thereto on a side thereof opposite the second component bottom. An inlet is provided to the flow channel as well as an outlet from the flow channel. A cover extends about the second component and is sealed to the second component peripheral wall in spaced relation to the second component bottom to define a fluid receiving space. The fluid receiving space is in fluid communication with the flow channel.
Thus, the components to be cooled may be cooled either by fluid circulating in the flow channel by pumping or by fluid in the fluid receiving space, that is, by either dynamic or static operation.
A preferred embodiment includes a heat transfer enhancing structure in the flow channel extending between and metallurgically bonded to the bottoms.
In one embodiment, each of the first and second components includes a peripheral flange extending about each peripheral wall at a location remote from the respective bottom of the component and the flanges are metallurgically bonded and sealed to one another.
Preferably, a fin is located within the fluid receiving space in heat transfer relation with the bottom of the second component and with the cover. Thus, heat rejected to fluid in the fluid receiving space is conducted to the walls and/or cover bounding such space to be dissipated into the atmosphere.
Preferably, the inlet and outlet are respective tubes which extend, in spaced relation through the fluid receiving space.
In one embodiment, the second component bottom includes spaced inlet and outlet ports to the flow channel and the tubes extend to and terminate just short of a corresponding one of the ports. In this structure, a small space between the ends of the tubes and the ports serves to establish fluid communication between the flow channel and the fluid receiving space.
In an alternative embodiment, the second component bottom includes spaced inlet and outlet ports to the flow channel and the tubes extend and are sealed to a corresponding one of the ports. Each of the tubes includes at least one aperture in a wall thereof opening within the fluid receiving space. In this embodiment, the apertures establish fluid communication between the flow channel and the fluid receiving space.
A highly preferred embodiment contemplates that there be a fin in the flow channel and even more preferably, the invention contemplates that the fin be metallurgically bonded to both of the component bottoms.
In a highly preferred embodiment, the fin is a lanced and offset fin.
In an alternative embodiment, a fluid guide is located in the flow channel for directing flow therein in a predetermined pattern between the inlet and the outlet.
Preferably, the flow guide includes at least one bead formed in at least one of the component bottoms and which extends toward and contacts the other of the component bottoms.
A highly preferred embodiment contemplates that the bead be formed in the second component bottom.
The invention also contemplates that the components and the cover be formed of braze clad aluminum and are brazed together.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.